perf: Add __slots__ to all DTypes

.pre-commit-config.yaml

@@ -47,6 +47,11 @@ repos:
       entry: python -m utils.check_api_reference
       language: python
       additional_dependencies: [polars]
+    - id: check-slotted-classes
+      name: check-slotted-classes
+      pass_filenames: false
+      entry: python -m utils.check_slotted_classes
+      language: python
     - id: imports-are-banned
       name: import are banned (use `get_pandas` instead of `import pandas`)
       entry: python utils/import_check.py

narwhals/dtypes.py

@@ -60,6 +60,8 @@ def _validate_into_dtype(dtype: Any) -> None:
 
 
 class DType:
+    __slots__ = ()
+
     def __repr__(self) -> str:  # pragma: no cover
         return self.__class__.__qualname__
 
@@ -152,30 +154,44 @@ def __hash__(self) -> int:
 class NumericType(DType):
     """Base class for numeric data types."""
 
+    __slots__ = ()
+
 
 class IntegerType(NumericType):
     """Base class for integer data types."""
 
+    __slots__ = ()
+
 
 class SignedIntegerType(IntegerType):
     """Base class for signed integer data types."""
 
+    __slots__ = ()
+
 
 class UnsignedIntegerType(IntegerType):
     """Base class for unsigned integer data types."""
 
+    __slots__ = ()
+
 
 class FloatType(NumericType):
     """Base class for float data types."""
 
+    __slots__ = ()
+
 
 class TemporalType(DType):
     """Base class for temporal data types."""
 
+    __slots__ = ()
+
 
 class NestedType(DType):
     """Base class for nested data types."""
 
+    __slots__ = ()
+
 
 class Decimal(NumericType):
     """Decimal type.
@@ -188,6 +204,8 @@ class Decimal(NumericType):
         Decimal
     """
 
+    __slots__ = ()
+
 
 class Int128(SignedIntegerType):
     """128-bit signed integer type.
@@ -208,6 +226,8 @@ class Int128(SignedIntegerType):
         Int128
     """
 
+    __slots__ = ()
+
 
 class Int64(SignedIntegerType):
     """64-bit signed integer type.
@@ -221,6 +241,8 @@ class Int64(SignedIntegerType):
         Int64
     """
 
+    __slots__ = ()
+
 
 class Int32(SignedIntegerType):
     """32-bit signed integer type.
@@ -234,6 +256,8 @@ class Int32(SignedIntegerType):
         Int32
     """
 
+    __slots__ = ()
+
 
 class Int16(SignedIntegerType):
     """16-bit signed integer type.
@@ -247,6 +271,8 @@ class Int16(SignedIntegerType):
         Int16
     """
 
+    __slots__ = ()
+
 
 class Int8(SignedIntegerType):
     """8-bit signed integer type.
@@ -260,6 +286,8 @@ class Int8(SignedIntegerType):
         Int8
     """
 
+    __slots__ = ()
+
 
 class UInt128(UnsignedIntegerType):
     """128-bit unsigned integer type.
@@ -274,6 +302,8 @@ class UInt128(UnsignedIntegerType):
         UInt128
     """
 
+    __slots__ = ()
+
 
 class UInt64(UnsignedIntegerType):
     """64-bit unsigned integer type.
@@ -287,6 +317,8 @@ class UInt64(UnsignedIntegerType):
         UInt64
     """
 
+    __slots__ = ()
+
 
 class UInt32(UnsignedIntegerType):
     """32-bit unsigned integer type.
@@ -300,6 +332,8 @@ class UInt32(UnsignedIntegerType):
         UInt32
     """
 
+    __slots__ = ()
+
 
 class UInt16(UnsignedIntegerType):
     """16-bit unsigned integer type.
@@ -313,6 +347,8 @@ class UInt16(UnsignedIntegerType):
         UInt16
     """
 
+    __slots__ = ()
+
 
 class UInt8(UnsignedIntegerType):
     """8-bit unsigned integer type.
@@ -326,6 +362,8 @@ class UInt8(UnsignedIntegerType):
         UInt8
     """
 
+    __slots__ = ()
+
 
 class Float64(FloatType):
     """64-bit floating point type.
@@ -339,6 +377,8 @@ class Float64(FloatType):
         Float64
     """
 
+    __slots__ = ()
+
 
 class Float32(FloatType):
     """32-bit floating point type.
@@ -352,6 +392,8 @@ class Float32(FloatType):
         Float32
     """
 
+    __slots__ = ()
+
 
 class String(DType):
     """UTF-8 encoded string type.
@@ -364,6 +406,8 @@ class String(DType):
         String
     """
 
+    __slots__ = ()
+
 
 class Boolean(DType):
     """Boolean type.
@@ -376,6 +420,8 @@ class Boolean(DType):
         Boolean
     """
 
+    __slots__ = ()
+
 
 class Object(DType):
     """Data type for wrapping arbitrary Python objects.
@@ -389,6 +435,8 @@ class Object(DType):
         Object
     """
 
+    __slots__ = ()
+
 
 class Unknown(DType):
     """Type representing DataType values that could not be determined statically.
@@ -401,6 +449,8 @@ class Unknown(DType):
         Unknown
     """
 
+    __slots__ = ()
+
 
 class _DatetimeMeta(type):
     @property
@@ -438,6 +488,8 @@ class Datetime(TemporalType, metaclass=_DatetimeMeta):
         Datetime(time_unit='ms', time_zone='Africa/Accra')
     """
 
+    __slots__ = ("time_unit", "time_zone")
+
     def __init__(
         self, time_unit: TimeUnit = "us", time_zone: str | timezone | None = None
     ) -> None:
@@ -521,6 +573,8 @@ class Duration(TemporalType, metaclass=_DurationMeta):
         Duration(time_unit='ms')
     """
 
+    __slots__ = ("time_unit",)
+
     def __init__(self, time_unit: TimeUnit = "us") -> None:
         if time_unit not in {"s", "ms", "us", "ns"}:
             msg = (
@@ -573,6 +627,8 @@ class Categorical(DType):
         Categorical
     """
 
+    __slots__ = ()
+
 
 class Enum(DType):
     """A fixed categorical encoding of a unique set of strings.
@@ -586,6 +642,8 @@ class Enum(DType):
        Enum(categories=['beluga', 'narwhal', 'orca'])
     """
 
+    __slots__ = ("_cached_categories", "_delayed_categories")
+
     def __init__(self, categories: Iterable[str] | type[enum.Enum]) -> None:
         self._delayed_categories: _DeferredIterable[str] | None = None
         self._cached_categories: tuple[str, ...] | None = None
@@ -655,6 +713,7 @@ class Field:
        [Field('a', Int64), Field('b', List(String))]
     """
 
+    __slots__ = ("dtype", "name")
     name: str
     """The name of the field within its parent `Struct`."""
     dtype: IntoDType
@@ -713,6 +772,7 @@ class Struct(NestedType):
        Struct({'a': Int64, 'b': List(String)})
     """
 
+    __slots__ = ("fields",)
     fields: list[Field]
     """The fields that make up the struct."""
 
@@ -782,6 +842,7 @@ class List(NestedType):
        List(String)
     """
 
+    __slots__ = ("inner",)
     inner: IntoDType
     """The DType of the values within each list."""
 
@@ -832,6 +893,7 @@ class Array(NestedType):
         Array(Int32, shape=(2,))
     """
 
+    __slots__ = ("inner", "shape", "size")
     inner: IntoDType
     """The DType of the values within each array."""
     size: int
@@ -910,6 +972,8 @@ class Date(TemporalType):
         Date
     """
 
+    __slots__ = ()
+
 
 class Time(TemporalType):
     """Data type representing the time of day.
@@ -935,6 +999,8 @@ class Time(TemporalType):
        Time
     """
 
+    __slots__ = ()
+
 
 class Binary(DType):
     """Binary type.
@@ -958,3 +1024,5 @@ class Binary(DType):
         >>> nw.from_native(rel).collect_schema()["t"]
         Binary
     """
+
+    __slots__ = ()

narwhals/stable/v1/_dtypes.py

@@ -48,6 +48,8 @@
 
 
 class Datetime(NwDatetime):
+    __slots__ = NwDatetime.__slots__
+
     @inherit_doc(NwDatetime)
     def __init__(
         self, time_unit: TimeUnit = "us", time_zone: str | timezone | None = None
@@ -59,6 +61,8 @@ def __hash__(self) -> int:
 
 
 class Duration(NwDuration):
+    __slots__ = NwDuration.__slots__
+
     @inherit_doc(NwDuration)
     def __init__(self, time_unit: TimeUnit = "us") -> None:
         super().__init__(time_unit)
@@ -81,6 +85,8 @@ class Enum(NwEnum):
        Enum
     """
 
+    __slots__ = ()
+
     def __init__(self) -> None:
         super(NwEnum, self).__init__()
 

pyproject.toml

@@ -210,8 +210,8 @@ extend-ignore-names = [
   "PLR0916", # too-many-boolean-expressions
 ]
 "tpch/tests/*" = ["S101"]
-"utils/*" = ["S311"]
-"utils/bump_version.py" = ["S603", "S607", "T201"]
+"utils/*" = ["S311", "T201"]
+"utils/bump_version.py" = ["S603", "S607"]
 "tpch/execute/*" = ["T201"]
 "tpch/notebooks/*" = [
   "ANN001",